Abstract

Ageing structures located in moderate to high seismicity regions are exposed to multiple natural stressors during their lifetime. Large earthquake events coupled with environmental aggressive agents increase the progressive failure probability of these structures. The accumulated damage during the main earthquake event might be exacerbated by its following aftershocks. This might result in catastrophic failure of these structures, and consequently, result in several socio-economic losses. Taking such progressive deterioration mechanism into consideration, the current study presents a framework to assess the vulnerability of ageing Reinforced Concrete (RC) frames subject to real Mainshock-Aftershock (MS-AS) ground motion sequences. Employing an advanced fibre-based finite element modelling technique, the nonlinear static and dynamic behaviour of a case-study RC frame with various ages is simulated under 48 real MS-AS record pairs. Quantifying corrosion-variant damage states, the age-specific fragility curves are developed for the considered structure under both single MS events and MS-AS sequences. It was found that the severely corroded RC frames are most likely to collapse before the second event comes up. Moreover, results show that the PGA ratio of AS to MS plays a critical role in seismic vulnerability assessment of highly corrosion-damaged RC frames.

摘要

位于中度至高度地震活动区域的老化结构在其生命周期中暴露于多种自然压力源。大地震事件加上环境侵蚀剂增加了这些结构的渐进式失效概率。主要地震事件期间的累积破坏可能会因随后的余震而加剧。这可能导致这些结构的灾难性故障，从而导致若干社会经济损失。考虑到这种渐进式劣化机制，本研究提出了一个框架来评估老化钢筋混凝土 (RC) 框架在实际主震-余震 (MS-AS) 地面运动序列下的脆弱性。采用先进的基于纤维的有限元建模技术，在 48 个真实的 MS-AS 记录对下模拟了具有不同年龄的案例研究 RC 框架的非线性静态和动态行为。量化腐蚀变化的损伤状态，在单个 MS 事件和 MS-AS 序列下为所考虑的结构开发了特定年龄的脆性曲线。结果发现，严重腐蚀的钢筋混凝土框架最有可能在第二次事件发生之前倒塌。此外，结果表明，AS 与 MS 的 PGA 比率在高度腐蚀损坏的 RC 框架的地震脆弱性评估中​​起着关键作用。结果发现，严重腐蚀的钢筋混凝土框架最有可能在第二次事件发生之前倒塌。此外，结果表明，AS 与 MS 的 PGA 比率在高度腐蚀损坏的 RC 框架的地震脆弱性评估中​​起着关键作用。结果发现，严重腐蚀的钢筋混凝土框架最有可能在第二次事件发生之前倒塌。此外，结果表明，AS 与 MS 的 PGA 比率在高度腐蚀损坏的 RC 框架的地震脆弱性评估中​​起着关键作用。